1. Field of the Invention
The invention relates to a device for establishing a galvanic connection between one or more conductors forming a first batch and one or more conductors forming a second batch, a transmission, consequent on electromagnetic radiation, between these two batches being purposefully blocked.
A device of the aforesaid type is used for example in combination with a screened room of the sort defined as the "Faraday cage", and containing communication equipment connected to the outer world of said room via electric conductors. Such conductors have been led through a wall of the "cage room" by means of such a construction that the desired screening effect of this cage room will not be affected in an inadmissible way.
2. State of the Art
A device of the sort described above and having connected between each pair of corresponding conductors of the first batch and the second batch a voltage-dependent .pi.-filter section with a coil connected in its longitudinal branch, and provided with an electrically conducting partition transversely to the direction of transmission is known from the Netherlands Pat. No. 173226.
The main purpose of a known device of the sort mentioned above is to protect communication equipment contained in a Faraday cage room against overvoltage in an economical way. Such overvoltage can be caused for instance an electromagnetic pulse (EMP) or by lightning. A high or high-energetic voltage induced in a conductor of for example the first batch by such a pulse is conducted to earth by the .pi.-filter section in stages and via the wall of the cage, so that the residual voltage or residual energy developed on the corresponding conductor of the second batch will be reduced to below a value admissable for the equipment connected to that conductor and contained in the cage room. A protection as described above appears to be insufficient for certain vulnerable communication equipment. Moreover, such a known device does not meet the necessary requirements with regard to: blocking a transmission, via the electric conductors, of voltages induced inside or outside the Faraday cage room consequent on electromagnetic radiation having a signal character; and transmission (impedance matching, attenuation etc.) of analog and/or digital signals.